Download The Atmosphere: Composition, Structure, and Temperature Earth

1/19/2015
The Atmosphere:
Composition, Structure,
and Temperature
Earth Science, 13e
Chapter 16
Stanley C. Hatfield
Southwestern Illinois College
Weather and climate
Weather
• Weather is over a short period of time
• Conditions are constantly changing
• State of atmosphere at any given point of
time and place
Climate
• Climate is over a long period of time
• Weather is collected over many years
• How the atmosphere “behaves” in a
certain place or region
Weather and climate
Elements of weather and climate
• Most important elements measured
regularly:
•
•
•
•
•
•
1. Temperature
2. Humidity
3. Cloudiness
4. Precipitation
5. Air pressure
6. Winds speed and direction
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Composition of the atmosphere
Air is a mixture of discrete gases
Major components of clean, dry air
•
•
•
•
Nitrogen (N) – 78 percent
Oxygen (O2) – 21 percent
Argon and other gases
Carbon dioxide (CO2) – 0.039 percent –
absorbs heat energy from Earth
• The Carbon that is used in Carbon dating
comes from this 0.039%
Proportional volume of gases
that compose dry air
Composition of the atmosphere
Variable components of air
• 1. Water vapor
• Up to about 4 percent of the air’s volume
• Forms clouds and precipitation
• Absorbs heat energy from Earth
• 2. Aerosols
•
•
•
•
Tiny solid and liquid particles
Water vapor can condense on solids
Reflect sunlight
Help color sunrise and sunset
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Figure 16.4a – p. 463
Dust storm vs. air pollution
Primary Pollutants
Composition of the atmosphere
Variable components of air
• 3. Ozone
• Three atoms of oxygen (O3)
• Distribution not uniform
• Concentrated between 10 to 50 kilometers
above the surface
• Absorbs harmful UV radiation (needed for life)
• Human activity is depleting ozone by adding
chlorofluorocarbons (CFCs) (used in making
aerosols and refrigerants)
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“Ozone hole” over the past 40
years
Moving on to:
Structure of the atmosphere
Demo – Inverted Water magic trick ☺
Demo – Water magic trick ☺
Discussion:
• How is the card holding the water in the
glass and preventing it from falling on the
floor???
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How pressure forms the base of
clouds
Structure of the atmosphere
Pressure changes
• Pressure is the weight of the air above
• Average sea level pressure
• Slightly more than 1,000 millibars
• About 14.7 pounds per square inch (psi)
• Pressure decreases with altitude (higher you go)
• One-half of the atmosphere is below 3.5 miles
(5.6 km) (see next slide)
• Ninety percent of the atmosphere is below
10 miles (16 km)
Atmospheric
pressure
variation
with altitude
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Structure of the atmosphere
Atmospheric layers based on
temperature
• A. Troposphere
• Bottom layer
• Temperature decreases with altitude – called
the environmental lapse rate
• 6.5°C per kilometer (average)
• 3.5°F per 1,000 feet (average)
• All weather is here
• Outer boundary is named the tropopause
Structure of the atmosphere
Atmospheric layers based on
temperature
• B. Stratosphere
• About 12 km to 50 km, jets fly here
• Temperature increases at top
• Outer boundary is named the stratopause
• C. Mesosphere
• About 50 km to 80 km
• Temperature decreases with height
• Outer boundary is named the mesopause
Structure of the atmosphere
Atmospheric layers based on
temperature
• D. Thermosphere
•
•
•
•
No well-defined upper limit
Fraction of atmosphere’s mass
Gases moving at high speeds
Increase of temperatures due to the absorption
of very short-wave solar energy by oxygen
above the stratosphere
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Thermal
structure
of the
atmosphere
Some diagrams
contain a 5th
layer called the
exosphere that is
really part of the
thermosphere
Activity 7.1 – Layers of the
Atmosphere
You have the rest of todays class and
tomorrow to complete this lab/activity
Earth-Sun relations
Earth motions
• Rotates on its axis
• Revolves around the Sun
Seasons
• Result of
• Changing Sun angle
• Changing length of daylight
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Tilt of the Earth’s axis
Earth-Sun relationships
Earth-Sun relations
• Special days (Northern Hemisphere)
• Summer solstice
• June 21–22
• Sun’s vertical rays are located at the Tropic
of Cancer (23½°N latitude)
• Winter solstice
• December 21–22
• Sun’s vertical rays are located at the Tropic
of Capricorn (23½° S latitude)
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Earth-Sun relations
Seasons
• Special days (Northern Hemisphere)
• Autumnal equinox
• September 22–23
• Sun’s vertical rays are located at the
Equator (0°latitude)
• Spring (Vernal) equinox
• March 21–22
• Sun’s vertical rays are located at the
Equator (0°latitude)
Characteristics of the
solstices and equinoxes
Earth-Sun relations
Some cultures have sacred sites that
align with the sun:
• Egyptians, Pagan, Mayan, Native
American, Buddhist, etc.
• Stonehenge, The Great Pyramids, Serpent Mound
(Ohio)
• http://belsebuub.com/articles/ancient-sacred-sitesaligned-to-the-summer-solstice
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Atmospheric heating
Heat is always transferred from warmer
to cooler objects
Mechanisms of heat transfer
• A. Conduction through matter (ie: touch)
• B. Convection
• Mass movement within a substance
• Heat rises, cold sinks
• C. Radiation (electromagnetic radiation)
• Through space
• Velocity: 300,000 kilometers (186,000 miles)
per second in a vacuum
Mechanisms of heat transfer
Conduction
When you heat a metal strip at one end, the heat
travels to the other end.
As you heat the metal, the particles vibrate, these
vibrations make the adjacent particles vibrate, and so on
and so on, the vibrations are passed along the metal and
so is the heat. We call this? Conduction
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Convection
What happens to the particles in a liquid or a
gas when you heat them?
The particles spread out and
become less dense.
This effects fluid movement.
What is a fluid?
A liquid or gas.
Fluid movement
Cooler, more d____,
ense fluids
armer
sink through w_____,
less
dense fluids.
In effect, warmer liquids and gases r___
ise
up.
Cooler liquids and gases s___.
ink
Water movement
Cools at the
surface
Cooler
water sinks
Convection
current
Hot water
rises
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Why is it windy along the coast?
Why are there off shore and onshore
breezes?
The third method of heat transfer
How does heat energy get
from the Sun to the Earth?
?
There are no particles between
the Sun and the Earth so it
CANNOT travel by conduction or
by convection.
RADIATION
Convection questions
Why does hot air rise and cold air sink?
Cool air is more dense than warm air, so the cool air ‘falls
through’ the warm air.
Why are boilers placed beneath hot water
tanks in people’s homes?
Hot water rises.
So when the boiler heats the water, and the hot water rises, the water tank
is filled with hot water.
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Radiation questions
Why are houses painted white in hot countries?
White reflects heat radiation and keeps the house cooler.
Why are shiny foil blankets wrapped around marathon runners at the end of a
race?
The shiny metal reflects the heat radiation from the runner back in, this stops
the runner getting cold.
1.
Which of the following is not a
method of heat transfer?
A.
Radiation
B.
Insulation
C.
Conduction
D.
Convection
2. In which of the following are
the particles closest together?
A.
Solid
B.
Liquid
C.
Gas
D.
Fluid
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3. How does heat energy reach
the Earth from the Sun?
A.
Radiation
B.
Conduction
C.
Convection
D.
Insulation
4. Which is the best surface for
reflecting heat radiation?
A.
Shiny white
B.
Dull white
C.
Shiny black
D.
Dull black
5. Which is the best surface for
absorbing heat radiation?
A.
Shiny white
B.
Dull white
C.
Shiny black
D.
Dull black
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More on:
Atmospheric heating
Mechanisms of heat transfer
• Radiation (electromagnetic radiation)
• Consists of different wavelengths
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•
•
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Gamma (very short waves)
X-rays
Ultraviolet (UV)
Visible
Infrared
Microwaves and radio waves
The electromagnetic spectrum
Atmospheric heating
Incoming solar radiation
• Atmosphere is largely transparent to
incoming solar radiation
• Atmospheric effects
• Reflection – albedo (percent reflected)
• Scattering
• Absorption
• Most visible radiation reaches the surface
• About 50 percent absorbed at Earth’s
surface
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Average distribution of
incoming solar radiation
Albedo
• The fraction of total radiation that is reflected by
any surface.
• Many clouds have a high albedo and therefore
reflect back to space a significant portion of the
sunlight that strikes them.
Clouds Reflect and Absorb Radiation
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Atmospheric heating
Radiation from Earth’s surface
• Heating of the atmosphere is termed the
greenhouse effect
The heating of
the atmosphere
Activity 7.1b – Greenhouse effect
Sign out a computer and do the
following activity and answer the
following questions.
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Temperature measurement
Daily maximum and minimum
Other measurements
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Daily mean temperature
Daily range
Monthly mean
Annual mean
Annual temperature range
Temperature measurement
Human perception of temperature
• Anything that influences the rate of heat
loss from the body also influences the
sensation of temperature
• Important factors are
•
•
•
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Air temperature
Relative humidity
Wind speed – ie: windchill
Sunshine
Controls of temperature
Important controls of atmospheric
temperatures
• Differential heating of land and water
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Land heats more rapidly than water
Land gets hotter than water
Land cools faster than water
Land gets cooler than water
• This affects our coastal breezes as we already
discussed…
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Controls of temperature
Other important controls
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•
•
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Altitude
Geographic position
Cloud cover
Albedo
Mean monthly temperatures for
two locations in Canada
Mean monthly temperatures
for two coastal locations
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World distribution
of temperature
Global temperature patterns
• Temperature decreases poleward from the
tropics (equator)
• Warmest and coldest temperatures occur
over land
World mean sea-level
temperatures in January
World mean sea-level
temperatures in July
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End of Chapter 16
HW:
p. 462 #1
p. 465 #1-3
p. 472 #2
p. 474 #2
p. 477 #1-2
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